It's common for there to be a slight discrepancy between the estimated duration of pregnancy based on your last period and the measurements from an ultrasound. The most accurate way to determine your gestational age is through an early ultrasound scan done within the first trimester. This scan can provide a more precise estimate of how far along you are in your pregnancy. As pregnancy progresses, individual variations in fetal growth can lead to differences between the two methods of calculation.
If you're unsure about which date to follow, it's best to consult with your healthcare provider. They will consider both sources of information and guide you accordingly. Remember that these estimates are just that - estimates - and may not always align perfectly due to various factors such as irregular periods or variations in fetal growth rates.
Ultimately, it's important not to stress too much about these small discrepancies in pregnancy duration. Focus on taking care of yourself and your growing baby by following a healthy lifestyle, attending regular prenatal check-ups, and discussing any concerns with your healthcare provider.